Now that you have your Stack of NUCs all built, updated, and connected to the wireless network, it is time to set them all up in the Ansible inventory so we can start doing things with them.

Purpose:

• Discover local hosts that the Ansible control node can access
• Add these hosts to our inventory

Power on all the NUCs. WiFi connectivity should make all visible to NUC 2, the Ansible control node.

Run the discovery script from the Ansible control node (NUC 2), and add the IP address to the inventory file ('hosts')

• example:
  • cd my-project
  • bash discover.sh hosts

• discover.sh

  if [ "$#" -ne 1 ]
  then
    echo "Usage: $0 filename.txt"
    echo "results will be appended to this file"
    exit 1
  fi
  OUTPUT=$1
  [[ ! -z "$OUTPUT" ]] && touch $OUTPUT || exit
  IPs=$(sudo arp-scan --localnet --numeric --quiet --ignoredups | grep -E '([a-f0-9]{2}:){5}[a-f0-9]{2}' | awk '{print $1}')
  for i in ${IPs}; do
    # set up SSH managment keys
    ssh-keygen -q -R $i && ssh-keyscan -H $i >> ~/.ssh/known_hosts
    # identify hosts ansible can access
    ssh -q -o PasswordAuthentication=No $i "hostname -I" && echo $i && echo $i >> $OUTPUT
  done

This is a quick and easy way to determine which ones weren't discovered: power off the ones that are working. Any of the NUCs still powered on has now been discovered.

ansible -i hosts all -a “poweroff”

Pull these NUCs for re-imaging/investigation. Next, power the “good” NUCs back on.

You now have a working Ansible environment! Continue to our First Ansible playbook with Ansible Update.

Since the lldpd package was installed, you can also discover the nodes using

• sudo lldpcli show neighbors
• Add the discovered hosts' IP address to the hosts file under [nodes]
• You will still need to add the hosts to the known hosts file

You can also discover ssh servers using nmap.

1. Install nmap
   • sudo apt install nmap -y
2. Run the following scan, replacing the network 192.168.1.0/24 with your Lab network
   • nmap -p 22 –open -sV 192.168.1.0/24
3. You can see that all the NUCs you installed have the same OpenSSH version. Add these IP addresses to the hosts file under [nodes]